Transformer for use with current-rectifying apparatus.



P. CONRAD.

TRANSFORMER FOR USE WITH CURRENT REOTIPYING APPARATUS. APPLIOATION FILED APEJO, 190a.

1,123,248. Patented Jan. 5, 1915.

INVENTOR v BY J ATTORNEY nit n ltlttl @A llunlli n nth-it,

IE1P3 Z%-.IL 1'K CONRAD, 01 SWiSSVALE, PENNSiTLVANIA, ASSIGNOB, 'BY MESNE ASSIGN- MENTS, TO WESTINGHGUSE ELECTRIC 5 TEANUFACTURING COMPANY, OF EAST PITTSBURGH, PENNSYLVMTIA, A CORPCEATION OF PENNSYLVANIA.

TRANSFORIJIER P6P, USE WE'IIEI CURRENT-RECTIFYING AKPARATUS.

1 123 241 8, Specification oi Letters Patent. Pg 'jjgm'fggd J 5 1915 Application filed April 10, 1988. Serial No. 426,311.

T ZZ h it may 0071mm; l The transformer comprises six coils a, 5, 6, 7, 55 Be it known that l, FRANK-CONRAD, a 8, and 9, of which the coils 4, 6, 7, and 9 citizen of the United States, and a resident constitute the secondary circuit, the said of Swissvale, ,in the county of Allegheny coils being connected in series and between and State of Pennsylvania, have invented a alternating current terminals 10 and 11 of new and useful Improvement in Transthe current-rectifying device. The middle 60 formers for Use with Current-Rectifying or other suitable intermediate point of the A r tu f hi h th following is a secondary Winding is connected to one terp ifi ati n I minal of the battery 1, and the other ter- 10 My invention relates to current-rectifying m nal Of the battery is connected to negative apparatus, and particularly to transformers pr dlrect current terminal 12 of the rectify- 65 that constitute a part of such apparatus. 111g device. One terminal of the coil 5 i The object of the invention is to provide connected to the connections between the a transformer of such structure and arrangecoils and 6 and one terminal of the coil 8 15 ment of parts that all other auxiliary devices is connected to the connection between the may be dispensed With and regulation of the C0llS 7 and 9, the said coils 5 and 8 being 70 operation of the rectifier readily'effected. subdivided by meansvor" a suitable number In order to sustain the unidirectional curof leads that are connected, respectively, to

rentderived froma vapor-rectifying device, Stationary contact terminals 13 to 524, in-

' it is usually necessary to provide a suitable elusive, of a regulating device 25. 'lhe regu amount of inductance in the direct current lating devices comprises further, a mov- 75 circuit, and in order to prevent small fluctuable arm 26 carrying conducting members ations of voltage from efiecting large varia- 2'? and 28 adapted to engage the said contact tions in the amount of current traversing terminals, as Well as conducting se ments 29 25 the rectifying device, it is also usually necesand 30 that are disposed adjacent thereto sary to either introduce a suitable amount and are connected to circuit conductors 31 so of ohmic resistance into the direct current and 32. The coils 5, 6, 9, and 8 therefore circuit or inductance into the alternating, constitute the primary circuit of the transcurrent'circuit. The functions alcove speciformer, and its active l ngth may be varied 30 lied have commonly been performed by sepby adjusting the position of the arm 26, the

arate devices, but in Patentl lo. $31,114 ll coils 6 and 9 losing common to both the 85 have proposed to so construct and arrange primaryand secondary circuits. the parts of a transformer? as to avoid the The magnetizable core of the transformer necessity oif employing other auxiliary de- 3 comprises a rectangular portion upon 35 vices. ldotve'ver, the-transformer there speopposite sides or legs of which the coils cifically shown ,and described is not Well 4 to 9, inclusive are mounted, three coils 96 adapted for use When the desired ratio of surrounding each leg, and an auxiliary centheprirnary to the secondary voltage is aptrail portion or leg 35 extending, between proximately one to one, because there would, the coils, from top to bottom and from i 40 in that case, he no separate or distinct "pathsside to side or the main core portion 34-, airfor the primary and secondary leakage, gaps of suitable Width being provided he 9 fluxes. ln the present application, is the tween the abutting edges of the core porspecific object to provide a transformer tions. lhe auxiliary core portion 35 proadapted for use When the ratio oi transior Yides, between the coils, leakage paths of mation is approximately one toone. relatively loW and suitable reluctance and Figure 1 of the accompanying drawing is such that the coils of the primary Winding, a diagrammatic view of a rectifying system or a part thereof, Will be surrounded by a embodying the invention, and Fig, 2 is a leakage flux that does not also surround simplified diagram of the same system. all of the .coils of the secondary Winding 50 A storage battery 1, of any desired nuinand, further, such that the secondary Win her of cells, is supplied with the charging ing, or a part thereof, Wlllbe surrounded current from current-rectifying apparatus by a leakage flux that does not also surcomprising a mercury-vapor or similar round the primary Winding". The effect of rectifying device 2 and a transformer 3. the former flux is to cause the desired drop former, as shown, are further of potential in the system-and the effect of the latter is to sustain the rectified current. The arrangement of the coils and core parts with-respect to each other is, in addition, such that, in making changes in the active length of the primary winding, i. e., changes in the voltage applied to the direct current circuit, the distribution and amounts of the leakage fluxes will be so affected as to cause the leakage volts per turn of the winding surrounding the primary leakage flux to vary in substantially the same ratio as the primary and secondary voltsper turn, with the result that the power factor of the rectifying apparatus remains approximately uniform under all conditions of operation. In order also, that the amounts of current supplied to the battery may vary through substantially the same range for each step of the regulator, it is desirable that the drop of potential in the svstem remain an approximately constant per cent. of the secondary voltage, and .in order that the minimum limiting value of the direct current at which the rectifying operation will continue may be approximately the same for each step of the regulator, z. e., in order that the sustaining effect may remain approX1- mately constant, it is desirable that the leakage flux which serves to sustain the rectified current should vary approximately in proportion to variations in the secondary voltage of the transformer. The structure and arrangement of the parts of the transsuch as to secure these results. I

\Vhen beginning the charging operation, the connections should be arrangedto produce a low secondary voltage, because of the low voltage of the battery in its uncharged condition, and, accordingly, the regulator arm 26 should occupy the position indicated, providing, of course, that the battery comprises the minimum number of cells which the apparatus is adapted to charge. The primary circuit then comprises all of the convolutions contained in coils 5, 6, 8, and 9, and, for purposes of illustration, it may be assumed that, under this condition, the convolutions in the primary and secondary circuits are equal in number. The main flux produced by the primary coils traverses a path indicated by the broken line 37, its direction during a-gi'ven half cycle being indicated by the pointers, 38. The secondary flux opposes the main primary flux and, by reason of the relatively low reluctances of the leakage paths provided by the core portion 35, as well as by reason of the fact that the primary coils 5 and 8 are not also included in the secondary circuit, primary leakage fluxes that do not surround the whole of the secondary Winding are caused to traverse paths indicated by the broken lines ,paths are permitted which, in turn,

39 and 40. These leakage fluxes have the same effect as the presence of inductive resistance between the transformer and the supply circuit, or of the presence of ohmic resistance in the direct current circuit, 2'. 6., of causing a drop of potential in the system for regulating purposes- These leakage fluxes, however, do not have any sustaining effect upon the rectified current, since they simply serve to shift the phase of the alternating current with respect to the electromotive force. By reason of the opposition of the primary and secondary fluxes and also because the primary and secondary circuits are not completely coincident, secondary leakage fluxes are also caused to traverse the relatively low reluctance paths provided by the core portion 35, the said paths being indicated during one half cycle of the alternating current by the lines 41 and 42, and during the other half cycle by the lines 43 and 4:4. The leakage fluxes indicated by the lines l1 and 42 are produced by the coil 7 and those indicated by the lines 43 and 4:4: are produced by the coil 4. It will be observed that the secondary leakage fluxes traverse the central portion of the core part-55 in the same direction for each half cycle of the alternating current. There is, therefore, no necessity of reversing the magnetism, or of fully re-magnetizing the said portion of the magnetic circuit, with the result that the increase of current in each half of the secondary Winding will be but slightly delayed. On the other hand, the decrease of current in each half of the secondary winding is considerably delayed by reason of the energy previously stored thereby in the portions of the magnetic circuit that are traversed by the sec.- ondary leakage fluxes, with the result that the uni-directional pr rectified currents, that are derived from the respective halves of the secondary Winding during successive half cycles of the alternating current, over.- lap. The secondary leakage flux, therefore, has the same effect as the presence of inductive resistance in the direct current circuit, 2'. e., of sustaining fied current or of preventing it from falling below a definite or predetermined value. The leakage fluxes indicated by the lines ll to 4%, inclusive, have no effect in causing a drop of potential in the system, because the direction of the said fluxes in the core portion 35 does not change. It will be observed that since a portion of the coils of the transformer are common to both the primary and secondary circuits and the remaining coilsbelong to the one or the other of said circuits, primary and secondary leakage fluxes that traverse distinctive permit of obtaining the desired regulating and sustaining eflects Within the transformer,

the direct or rectias aaaa even though the ratio of transformation is substantially one to one. The leakage fluxes indicated by the lines 41 to 44., inclusive, have no effect in causing a drop of potential in the system, because the direction of the said fluxes in the core portion 35 does not change. As the battery becomes charged, its voltage increases and the amount of charging current accordingly decreases. When the current delivered to the battery has decreased to a predetermined value, the sustaining efiect afforded by the leakage fluxes indicated by the lines 41 to l-l, inclusive, becomes insufficient to sustain the rectified current, and the rectifying process, therefore, is interrupted. If the battery is not, at that time, fully charged, the regulator arm 26 should be moved another step in a clockwise direction for the purpose of removing portions of the coils 5 and 8 from the primary circuit- .of the transformer, which, in turn, serves to increase the voltage applied to the secondary circuit. In general, the mode of operation remains as previously described, though, upon removing portions of the coils 5 and 8 from the primary circuit of the transformer, a greater amount of primary the path indicated by the line 39 and a smaller amount to traverse the path indi- 'cated by the line lO, while the total amount of leakage is increased. The changes in the amount and distribution of the leakage fluxes is such that the leakage volts per turn of the winding surrounding the primary leakage flux change substantially in direct proportion to the change in the primary and secondary volts per turn, and also such that the change in the sustaining effect aiforded by the fluxes indicated by the lines 41 to 44, inclusive, is substantially proportional to the change in the secondary voltage. The power factor of the apparatus, therefore, remains substantially the same as before the movement of the regulator arm and the rectifying operation will continue until the rectified current has decreased to substantially the same value as that at which the operation ceased before movement of the regulator arm. Since the drop of potential in the system is proportional to the product of the primary leakage flux and the number of turns of the winding surrounding the leakage flux, this result would not occur, if the distribution of the leakage flux were not altered at the same time it is changed in amount, or at the same time that the secondary voltage is changed. If the battery cannot be fully charged with the conducting members 27 and 28 in engagement with contact terminals 14 and 23, respectively, the regulator arm should be moved step by step in a clockwise direction until. the

leakage flux is caused to traverse series-connected coils, desired degree of charge is obtained. In continuing the movement of the regulator arm in a clockwise direction, the total amount of primary leakage fillX increases and more of the fluX indicated by the line 40 is gradually divert ed into the path indicated by the line 39, with the result that the conditions above described continue to prevail.

The range of direct current voltages obtainable from the apparatus is such, or may be such in practice, as to adapt it vto fully charge a storage battery the voltage of which may change considerably from no-charge to fully charged condition, or to adapt .it for use in the charging of batteries comprising considerably difierent numbers of cells.

llhile the invention is primarily intended for use in connection with the charging of storage batteries, it is not limited to such use, but'is equally applicable in connection with apparatus employed for other purposes.

I claim as my invention:

1. A transformer comprising a magnetizable core having two legs, and a plurality of coils upon each leg, those occupying the extreme positions being connected in series and those occupying intermediate positions being subdivided and connected to the common connections of the coils between which they are located.

2. A transformer comprising a magnetizable core having two legs, and a plurality of coils upon each leg, those occupying extreme positions being connected in series and those occupying intermediate positions being subdivided and connected to the common connections of the coils between which they are located, in combination with means for adjusting the points of connections to the subdivided coils.

3. A transformer comprising a magnetiz able core having two legs, a plurality of coils upon each leg, those occupying the extreme positions being connected in series and those occupying intermediate positions being subdivided and connected to the common connections of the coils between which they are located, and means providing leakage paths between the coils.

a. A transformer comprising a magnetizable core having two legs, and a plurality of coils upon each leg, those occupying the extreme positions being connected in series and those occupying intermediate positions being subdivided and connected to the common connections of the coils between which they arelocated, the subdivided coils and those at the extremities of the series comprising approximately the same number of c'onvolutions.

5. A transformer comprising two pairs of and two other coils each of whichis symmetrically disposed be tween two of the series-connected coils and has a terminal connected to the'ad3acent terminals of the coils between which it is located. 1

6. A transformer comprising a magnetizable core, a plurality ,of series-connected coils, other coils connected to the common connections of coils of the said series, and means providing leakage paths between the coils.

7. A transformer comprising a magnetizable core, a plurality of series-connected coils, other coils connected to the common connections of coils of the said series, certain of said coils being subdivided, and means providing leakage paths between the coils and arranged to cause variation in the distribution of the leakage fluxes when adjustment of the points of connection to the subdivided coils is effected.

S. A transformer comprising a magnetizable core having two legs, a plurality of coils upon each leg, those occupying the extreme positions being connected in series and those occupying intermediate positions being sub-divided and connected to the common connections of the coils between which they are located, and means providing a relatively low reluctance leakage path around each of the coils. o

9. A transformer comprising a magnetizable core having two legs and yoke portions,

a plurality of coils upon each leg, those occupying the extreme position being connected in series and those occupying intermediate positions being sub-divided and connected to the common connections of the coils between which they are located, and magnetizable material interposed between the coils and extending adjacent to the yoke and leg portions of the core.

in testimony whereof, I have hereunto subscribed my name this 27th day of March,

' FRANK CONRAD. WVitnesses:

R. B. INGRAM, BIRNEY HINES. 

